Original subtitles

STEVE BACKSHALL: Whales... (WHALESONG)

..ocean giants, ancient mariners.

Their songs, majesty and sheer size

fill us with joy and awe.

In their vast shadow,

a human can feel very small.

They were here long before us...

..caring for their young...

..hunting...

..voyaging.

But now we are changing their world.

So now I want to see through their eyes,

meeting them on their terms

to find how their future and ours are inseparable.

Whales are the largest mammals on the planet.

Their streamlined bodies...

..powerful tail flukes...

..and huge reserves of energy...

..make them perfectly evolved...

..for a life of ocean crossing voyages.

Migrations.

(WHALESONG)

Whales undertake the most epic journeys of any animals,

with some species travelling thousands of miles every year,

following routes their ancestors have used for generations.

For centuries, their seasonal journeys,

and the reasons they chose certain destinations...

..were a mystery.

Now, for the first time,

science has mapped their migrations,

revealing whale superhighways

that crisscross our planet.

I want to know if this offers new insights

into why whales travel so far...

..and what's happening as they try to navigate our changing oceans.

I'm starting my journey in Tahiti, in French Polynesia,

an important hotspot on the whale migration map.

(RHYTHMIC CHIRPING)

Tahiti is an island nation,

surrounded by miles and miles of open pacific.

Perhaps best known for its dramatic and iconic surf.

The swell that creates these waves

has travelled for thousands of kilometres to reach here.

But humpback whales, one of our planet's greatest migrants,

travel even further, all the way from the chilly waters of Antarctica,

to come here for the most important moment of their lives.

This may seem like paradise to us,

but Antarctica is where the humpback's food is.

So why do females leave that behind...

..and travel thousands of kilometres to give birth here?

This is the most commonly seen sight of the humpback.

Indeed, it's what gives it its name,

that distinctive humpback shape.

Right now, this female is just hanging at the surface,

taking it easy while the small calf moves around her.

This mother has earned her rest.

It took 3 months to swim here,

and then she gave birth to her one-tonne baby.

I want to see how she's getting on.

(WHALESONG)

Down here, I can feel the reason Tahiti is so appealing.

The water's calm and warm.

Coming here means she can spend less energy keeping herself warm...

..and more energy nursing her calf.

They look so calm and tranquil.

For the female, though, these are really tough times.

While she's here feeding her calf,

she's spending enormous amounts of energy

and not feeding at all.

Her fasting can last 9 months...

..so she must conserve every bit of energy.

While she rests,

her calf is free to discover the world around it.

The female is almost saying,

"Go on now, go and play with your new friends."

Under Mum's watchful eye,

the calf uses its newfound freedom...

..to play.

Just a few months old,

this calf is getting to know its own body.

Soon, it must swim to Antarctica

on its first migration.

The calf just wouldn't leave us alone.

It's one of those once-in-a-lifetime moments

when an animal sees you, seeks out your company

and wants to interact with you.

It's totally on their terms.

I think that's probably,

in 25 years working with animals,

the best thing that's ever happened to me.

Whales travel here because these waters...

..offer optimum conditions.

But we are changing that.

The planet is heating up.

Recently, the world's ocean surface temperature

was at its highest since records began.

If the waters warm beyond their tolerance,

humpbacks could lose these perfect nurseries forever.

Over to the northeast of the Pacific,

grey whales face one of the longest journeys of all.

Up to 10,000km

from Alaska all the way to Mexico.

It's winter,

and this female has been heading south for two months.

Her goal was to reach warm, safe waters before she gave birth.

But her calf has been born on the way.

It's the last thing she wanted.

Changing sea ice in her Alaskan feeding grounds

impacted the food she relies on.

Forced to feed further north,

her migration is longer than normal...

..and taking more time.

Just days old...

..her baby is unprepared for the journey.

But they must keep moving.

She tries to support him.

But he is still weak.

Their plight was filmed off the Californian coast,

1,000km short of their safer Mexican birthing lagoons.

It's not known if they ever made it.

Whales need better protection for their habitats...

..and the superhighways that connect them.

I want to see what's being done.

The peoples of Polynesia are some of the world's finest seafarers,

able to cross entire oceans

in small boats not much bigger than this va'a or outrigger.

Just as they sometimes had to leave the sanctuary of the lagoons

and head out into the terrors of the big blue,

the humpbacks too, can't stay here forever.

They're going to have to set off

on one of the most dangerous journeys in nature.

While it's an ideal nursery,

Tahiti offers nothing in the way of food.

This female has barely eaten since she left Antarctica six months ago.

She must now return to the freezing waters of the South.

(GROANING)

Her young calf will join her.

It's a huge undertaking,

swimming over 6,000km through open ocean.

To survive, the calf will need to be in peak physical condition.

Two here! Two here!

Mother and calf, I think, breaching in front of us.

Breaching is a really interesting form of behaviour.

Here in these waters you often see the youngsters, the calves breaching,

and they'll go over and over and over again,

and the energy they need to expend to get out of the water is immense.

Research suggests this could be a form of training.

Building the strength needed

for the vast migration that lies ahead.

Eventually, the youngsters are strong enough

to make their epic journey to Antarctica,

but it's a trip that's fraught with danger.

The discovery of whale superhighways comes at a critical time...

..as their long journeys

put them right in the path of our increasing boat traffic.

Here in Nanuu Bay on Tahiti's North coast,

the problem is clear.

For humpback whale calves, it's incredibly challenging.

They can't dive as deep as their mothers.

They spend much more time nearer the surface.

And ferries like this

are heading back and forth between these islands all the time,

putting these animals in constant peril.

The risk of collision

turns this sanctuary into a danger zone.

A boat this size has hundreds of tonnes of force behind it.

Being struck by that

is gonna be fatal for any whale, no matter how big it is.

Around the world,

ship strikes kill dozens of whales each year.

The number of vessels is rising.

By 2050, shipping traffic is projected to increase

up to 1,000%.

For migratory whales, their ocean world...

..has become a minefield.

The search for solutions is underway,

and one success story can be found in New Zealand.

(SHIP HORN BLARES)

The Port of Auckland was a whale-collision hotspot.

The shipping routes plough right through the habitat

of resident Bryde's whales.

These sleek hunters

consume schooling fish in shallow waters.

When they can catch them.

But this means they spend a lot of time near the surface...

..in the path of passing ships.

Professor Rochelle Constantine

is an expert in marine mammal conservation.

CONSTANTINE: That's an example of the ships that transit through the Gulf.

If this ship was going full speed,

the whales would stand no chance if they were in the path of this ship.

About 15 years ago,

we had around two to three whales a year

washing ashore with injuries consistent with a ship strike.

Her solution was simple...

..to persuade shipping companies to reduce speeds

to just 10 knots in specific zones.

Since they've slowed down,

no whales have been found dead from ship strike.

Whales have time to get out of the way.

Such a great conservation win.

Helping whales doesn't always have to be complicated

or costly.

And the more we discover about their superhighways,

the better we're able to make positive change.

Whales migrate for many reasons.

And one of the strongest motivators,

is the need to mate.

This is a southern right whale.

The white callosities on their head

are as unique as fingerprints.

(VOCALISES)

This one is a female.

She's travelled thousands of kilometres from the Southern Ocean,

to Argentina's Valdes Peninsula.

She's not alone.

Over 1,500 southern rights arrive each year in late summer.

Calm shallow bays

offer ideal conditions to breed in

and to nurture newborn babies.

But not every female is here to give birth.

This one is looking to meet a wide range of male suitors.

She has no intention of mating with the first male to approach.

Instead, she attracts several males

who have to compete for her attention.

Rolling on her back,

she keeps her genital region out of reach

until she's ready.

She's looking to test their agility and stamina.

When a strong suitor has jostled into the closest position...

..she rolls onto her front.

This is his chance to mate with her.

But when another male takes his place...

..she mates with him too,

sometimes repeatedly.

And the competition for paternity continues inside her body.

Their one-tonne testicles

produce huge quantities of sperm

to displace that of their rivals.

It's all part of her strategy.

Males that mate the most times

and produce the strongest sperm...

..have the best chance of fathering her next calf.

These waters are also vital to southern right whales

for calving.

But infant mortality is on the rise here,

and I want to find out why.

Human activity is transforming the oceans.

And whales are facing the consequences.

In Argentina, calm, shallow waters

used to offer newborn calves safety from predators...

..but that is changing.

Just metres from shore, are a southern right whale mum and calf.

The mother travelled up to 3,000km

to find a safe, quiet place to give birth and nurture her baby.

She provides up to 300 litres of milk a day.

But the peace of this tranquil hideaway...

..is being shattered.

Kelp gulls have learned to feed

on the skin and blubber of whales.

And, as calves need to surface more frequently to breathe,

they suffer the most.

Although it's the gulls that do the damage...

..we've played our part.

Birds first attracted here by waste,

from landfill and fish processing...

..have developed a taste for whale flesh.

Now the back of almost every calf carries open wounds.

(GROANING)

Time for resting and feeding is lost to avoiding gulls,

and calf mortality is on the rise.

Soon these infants must embark

on the long migration to the feeding grounds...

..their mothers came from.

The most injured are the least likely to survive.

We've come a long way in our knowledge of whale superhighways.

But we need to know more.

Rapidly advancing technology could help further our understanding.

A good place to see for myself is this vital pit stop

for whales in the Atlantic - the Azores.

This is a social group of female sperm whales

with a couple of youngsters and juveniles.

Their large heads hold a brain six times the size of a human's.

But our knowledge of how they use it is limited.

But one of the ways that science is starting to unravel

the mysteries of the sperm whales' secret life is using sound.

I have here a highly directional hydrophone.

It's essentially a normal hydrophone

welded onto a dog's bowl.

I'm gonna listen out and see if I can hear anything.

Ah, there! There, there!

(SLOW-TEMPO CLICKING)

(RAPID CLICKING)

So what I'm hearing is a ticking sound.

This is "coda", which is a kind of dialect,

a language that females use when they're at the surface.

These series of clicks are exchanged in social encounters,

much like people talking when they meet.

(SLOW—TEMPO CLICKING)

(CLICKING QUICKENS)

Some codas are highly variable.

But others are more uniform,

a dialect shared by all whales in the same region.

While we understand the basics,

their full meaning has always been beyond our grasp.

But now scientists are using artificial intelligence

to try to decode coda.

The results could transform our understanding of sperm whales.

And one day, may even enable us to talk to them.

Elsewhere, other high-tech tools are shedding light

on whales' long-distance journeys.

Until recently,

tracking devices that give us data while they're on the move

were fairly limited.

Pioneering scientist Dr Iain Kerr,

has made it his mission to change that.

DR KERR: I've dedicated 32 years of my life to whales.

We developed a system whereby we actually attach

a data and a camera tag to a whale using a drone.

In Mexico's Sea of Cortez,

he and his team are looking for the largest whale of all -

the blue whale.

So let's come out here, head up along the inside of the coast

where we can see the blows against the shoreline.

MAN: Here we can fly the drone, no problem.Exactly.

(SPEAKING IN SPANISH)

Many blue whales migrate here in winter,

from the northern Pacific Ocean.

Oh, hold on.

Over here. Yeah. There's a whale over here.

Where? To the right of the island.

Alright, the game is on.

Iain's technology could help show how

they're reacting to human influences, like noise and shipping.

Tags like this are gonna definitively tell us

what affects the whale.

The tags record a whale's movement and orientation in the water,

but that's not all.

So we've got a heart-rate monitoring tag on here now,

which is pretty exciting.

They also give information about the whale's health

while it's swimming.

It's been done before but never done with a drone,

so fingers crossed.

Using drones reduces the need to get close to whales with boats.

Good job, team.

Heart-rate monitoring tag is on a whale, deployed by a drone.

First time ever. Alright!

The tag causes no harm

and will automatically detach in several hours.

We collect data in the hope that we could effect change.

The exciting thing for us now

is to assemble this data into a picture that makes sense,

not just for understanding how they live their lives,

but how we can help conserve these animals.

As more whales are tagged...

Tag on. Yay! WOMAN: Yay!

..Iain's getting new insights into behaviour...

..how whales are affected by humans...

..and where and when we should focus our efforts to protect them.

To find out more about change,

I've headed north.

The Arctic Ocean is critically important

for the survival of many whale species.

With seasonal abundance of everything from plankton to algae to fish,

drawing in long-distance migrants from thousands of miles away.

But the Arctic is changing faster due to climate change than anywhere else.

How will this impact migrating whales?

My journey following whale superhighways...

..began in the tropics.

Now I'm in Norway,

a seasonal destination

for migrating humpbacks of the North Atlantic.

These arctic seas are completely mirror flat,

but out in the fjord, there is a frenzy of activity taking place.

(WHALESONG)

Humpbacks feed on krill and small fish,

such as herring and capelin.

Darkening the water,

shoals can contain hundreds of millions of fish.

A rich reward at the end of their long journey...

..10,000 humpbacks come to feast.

While here, they must store enough energy

to last the next six months.

Having swum thousands of kilometres to get here,

it won't be long before they'll have to return

to breeding and birthing grounds

in Cape Verde and the Caribbean.

To see what state they're in after the journey,

I need to get nearer.

I'm gonna take a paddleboard and coast in,

and hopefully that should give us an intimate glimpse

of these animals resting at the surface.

I have to be really careful

not to disturb them at this critical time.

So I intend to wait and see if they come near me.

The spouts are going off like cannon fire,

one after the other.

Their billowy spray just covers you.

Woah!

They're right underneath me!

Well, that was much, much closer

than I expected, or wanted.

Totally overwhelming!

To us, the Arctic Ocean may seem

so challenging, so brutal,

but to the humpbacks, this is an oasis.

It's truly one of the most impressive spectacles on our planet.

So we're getting towards the last light of the day,

even though it's no more than half past one in the afternoon.

There could be 50, or even 60 humpbacks here now.

And they've assembled around our boat.

It's a very rare opportunity.

Don't often get...

this amount of animals packed in close together like this.

MAN: Jump, guys. All good.

All three in the water.

This is one of the few places on Earth

where I've seen humpbacks in these numbers.

They look healthy and well-fed...

..but Arctic waters are getting warmer...

..and I want to know if these whales are being affected.

Professor of Marine Biology Audun Rikardsen

is investigating this population.

Now we are up to taking biopsies -

skin samples from humpbacks.

His research gathers a range of information on individuals.

Then we need to load this. This is the biopsy,

where we take the skin sample and also lift some blubber.

OK. Go. Go. Go. Go.

That direction. Follow my hand.

Lovely. Follow. Follow.

Yeah, keep that.

Yes. It's there.

The biopsies are harmless...

We got it. Yeah, we have it. We have it.

..and provide important data.

See here, that's the blubber,

and inside here is also a piece of skin.

This is a good sample.

And his samples also reveal the sex of the humpbacks that migrate here.

It seems to be mostly females that are here,

and some of them are pregnant.

The females need that extra energy to feed the calves.

For pregnant females,

it's vital to fuel up before heading to their birthing grounds.

But according to Audun, things are changing.

What we see, when the ocean heats up,

we see that several of these fish species migrate north

and they move their spawning areas.

So that means that the whales have to follow.

And for those that migrate a long distance,

they will have a longer migratory distance.

Is this something that we are thinking will happen in the future,

or is that something that's already happening now?

It's already happening now. It will have a dramatic effect on the whales.

The movement of fish stocks is creating challenging, longer journeys

for these migratory humpbacks.

But they're not the only ones that rely on the herring.

Orca come here, as do we.

And I witness something I've never seen before.

There's a juvenile humpback,

which has about 10 orca around it.

It's right below us. Just below us.

It's here. You can see the underside of the fins.

(VOCALISING)

It's slapping with that giant tail.

That's its biggest defensive weapon.

It's hard to know why the orca are pursuing the humpbacks.

These are supposed to be fish-feeding orca...

..not focused on mammal prey.

But clearly they've decided

there's something about this humpback that interests them.

These species compete for food,

so is this just bullying,

or could the orca be actively targeting a weak individual?

This has really stepped up a notch,

and they're battering it,

biting its fins and tail. (HUMPBACK GROANS DEEPLY)

And you can hear its distress.

We don't know if competition for food will increase,

or if we'll see more of this extraordinary behaviour.

We do know, though, that our Arctic seas are changing

faster than anywhere else on our planet,

and the future certainly holds fresh challenges

for the great nomads of our seas.

Throughout my journey,

I've seen the difficulties migrating whales face on their travels.

Only those completing these voyages

can fulfil all of life's needs.

From finding food...

..to mating...

..and raising their young.

Just as we start to understand the use of superhighways,

they're being rewritten by our changing planet.

But if we can protect both their highways and their destinations...

..and if we can keep ocean temperatures within safe limits...

..we'll afford whales a fighting chance...

..and secure their future for generations to come.

Of all the ocean voyagers we set out to film,

we knew one would be the hardest to get.

Pregnant humpbacks travel thousands of kilometres to give birth

in the tropical waters of Tahiti.

But filming the intimate relationship between a mother and her newborn calf

required the utmost sensitivity.

There's lots of whales out there,

but the majority of them are not gonna be interested in you,

so finding the right one is what it's all about.

Even then, you can't just jump in and swim up to them.

Any splash or strange noise could be startling.

To capture them on camera, you need to win their confidence

and wait for them to come to you.

Mother and cub just came up right in between us and our support boat.

Whale expert and camera operator Denis LaGrange

was our guide to choosing the right whales.

What do you think, Denis, shall we get in?

DENIS: I think maybe we should try a drop.

You think? Yeah. Let's go.

But when we got in the water,

they weren't interested in us.

We headed over, the calf was playing on the surface...

..but, um, the mum came up...

(WHALESONG) ..just as we got there and took it away.

A tantalising taste of what could be

for camera operator Rob Taylor.

ROB: It's the first time we've been in with a calf,

and they've just came up slowly in between us,

had a breath and just slowly moved away.

It was amazing.

For the next six days, we scoured 100km of coastline

looking for a mum and calf

that were comfortable in our company.

We were just too late. Just too late.

But though we had fleeting encounters...

They were not stable.

They move as soon as we get into the water. Yeah.

..the whales never stayed long enough to give us what we needed...

This is getting tricky.

..and time was running out.

We're on Day 6, and we still haven't had...

a decent encounter.

So we just keep hoping that we're gonna get that one individual

as interested in us as we are in them.

No one wanted to admit it might not happen.

As we head out on our last morning,

suddenly a mother and calf

appear just 100m from the harbour.

A pair of whales just popped up right alongside the boat,

and I do mean right alongside the boat.

Everything now rides on the decision about when to enter the water.

In this situation, as much as your heart's racing,

and you're dying to jump in and start swimming, it pays to be patient.

It's your call, Denis. You know them better than we do.

I don't know them personally.

(LAUGHTER) I am sorry, Steve.

I think we should give one more try.

Cautiously, we slip into the water.

(WHALESONG)

The calf is fascinated with us.

It comes right up to the team

and begins to twirl playfully.

It's the encounter of a lifetime,

and Denis and Rob finally get the shots

wildlife camera teams dream about.

That was unbelievable!

That was so close.

Enabling us to tell the story of these incredible voyagers,

and why they travel so far to come here.

As a human, you're going, "This is amazing."

And as a cameraperson, you're going, "Is it recording?

Is it in focus? Is it exposed right? Is Steve in the shot?"

The mother decides the encounter, you know. We didn't decide.

I am so proud of the team.

You know we've really stuck at this.

Ten days we've been doing this, and we've just waited

for the right moment and the right whale. Didn't push it.

And it's all paid off.

(VOCALISES)

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